In the event of serious health disorders or after major medical interventions, such as after a heart transplant, long-term uninterrupted monitoring of the patient""s condition is indicated for early detection of a possible rejection reaction. With a view to the quality of life of the person affected, and also for reasons of capacity and costs, this should occur outside a clinic.
Also with individuals with implanted electronic medical devices, such as cardiac pacemakers, constant monitoring of the condition of the patient or of the device is often necessary and usually at least the capability of immediate signaling of life-threatening conditions of the patient or of the device, associated with simultaneous determination of the whereabouts of the patient, is desirable.
For various applications, there are a large number of known arrangements for outpatient monitoring.
U.S. Pat. No. 5,626,630 describes a medical telemetry system operating with an implantable quasi-passive transponder which includes, in addition to the transponder, a relay device to be worn on the body of the patient and a remote monitoring station.
German patent application P 197 58 393.8 of the applicant describes an arrangement for patient monitoring in which a patient device is activated automatically in response to a specific position of the patient for data transmission to a central monitoring center, in particular via a telephone network.
WO 97/00708 describes an advanced, very expensive system for worldwide patient positioning and for data transmission of implanted devices to suitable evaluation points. To determine the geographical position of patient based on the satellite navigation system GPS, the system includes a special receiver which the patient carries.
In the same expensive manner, the determination of patient location occurs in the cardiac stimulation system with expanded communication and monitoring capabilities according to U.S. Pat. No. 5,720,770, which moreover also provides for the use of the fixed telephone network or a mobile phone network for the transmission of relevant data.
The object of the invention is to report a simple, economical arrangement for patient monitoring, in particular of individuals with implanted electronic medical devices, which enables an adequately accurate determination of the whereabouts of the patient in the event of an emergency.
The object is accomplished by means of an arrangement with the characteristics reported in claim 1.
The invention includes the underlying idea of using the position-relevant data constantly internally available in a cellular mobile phone network for position determination of the patient and to do without special means for geographic position determination.
This idea is based on the one hand on the fact that at the operating company of a mobile phone network, the geographic coordinates of all base stations used are present and each remote device addressed is, of course, located within the transmission and receiving range of at least one base station, but usually a plurality of base stations at the same time. On the exchange level of the mobile phone system, the information as to which base station is involved is also present, such that approximate locating of the patient is already possible on the basis of the base station position data.
Moreover, in a modem mobile phone system, to implement automatic handover between different base stations, among other things, measurements of the signal propagation time at least to the base station currently active for the terminal in question occur such that additional position-relevant information is present in the system with propagation time information. If the propagation times to a plurality of adjacent base stations are measured at the same time, it is possible to obtain a very precise determination of the location of the terminal in question and thus of the patient from their position data and the associated propagation time values. The propagation time data may, depending on the concrete organization of the network, be queried on the terminals or at the base stations and possibly also at the exchange level.
And finally, the fact that the base stations usually operate with directional antennas offers a capability for refined position determination of the patient by determining and evaluating which antenna of the base station the connection with the patient-terminal is made with.
Starting from these considerations, it is reasonable for the monitoring center of the patient care system to be connected for reception of position data of the mobile phone terminal (in addition to the connection with the patient terminal) with a mobile phone exchange or the center of the mobile phone network.
Position data evaluation means for evaluation of propagation time data reflecting the distance of the mobile phone terminal from at least one base station are allocated to the monitoring centers along with coordinate data of the active or reachable base station(s) of the mobile phone networkxe2x80x94which includes the variant that these evaluation means lie within the response range of the mobile phone network operator and only the result data are feed into the patient monitoring system.
From the above basic ideas, it is clear that the simultaneous processing of propagation time data relative to a plurality of base stations is preferred. A determination of the signal propagation times to a plurality of base stations can, if not provided anyway in the standard protocol of the network used, be organized within the framework of a special protocol which is agreed to between the operator of the patient monitoring system and the operator of the mobile phone network. The evaluation by means of known trigonometric positioning procedures takes place most expediently at the patient monitoring center.
Another preferred embodiment consists in that the position determination unit has propagation time storage means to store the time variation of propagation time data over a prespecified period of time. Thus, it is possible to reconstruct a path of movement of the patient within the transmission range of the current base station (or plurality of base stations), which is helpful for accurate determination of the current position. For this, it may, in particular, be reasonable to select the time period to extend back far enough that earlier connections to other base stations are detected with reasonable probability.
Based on the above, another preferred embodiment consists of the position determination unit having means for detection of the antenna allocation upon connection of the mobile phone terminal with the active base station.
For the embodiment of the invention, expediently a well-designed GSM mobile phone network must be selected, according to current technology, in particular a D network or the E network. In the interest of the most gap-free patient monitoring globally possible, a connection of the patient monitoring system to all established mobile phone networks with a high degree of area coverage is particularly advantageous.
In order to keep the power requirement of the patient unit (of the mobile phone terminal) and thus the maintenance cost low and finally in order to also enable a high degree of miniaturization, activation should occur only as needed or in any case also for test purposes at relatively long intervals.
Consequently, advantageously, a parameter monitoring unit connected with the body signal processing unit or the therapy device to monitor the values of the physiological parameter or an operating parameter of the therapy device and switching means connected with the output of the parameter monitoring unit or activation of the mobile phone terminal in response to the detection of an abnormal value are provided. Moreover, manually or acoustically activated switching means for activation of the terminal by the patient himself may be provided.
A particularly useful application of the invention is found in the case of an implanted cardiac therapy devicexe2x80x94such as a cardiac pacemaker for antibradycardiac or antitachycardiac stimulation of the heart or an automatic defibrillator or cardioverterxe2x80x94with a connected stimulation or shock electrode arrangement, with the body sensor and the downstream body signal processing unit designed to pick up and process heart signals for detection of cardiac arrhythmias, in particular life-threatening ones (e.g.: ventricular fibrillations or prestages thereof).
The body signal processing unit here includes, in particular a rate determination and evaluation unit for the determination and preferably also for retrospective evaluation of the heart rate as a physiological parameter and the parameter monitoring unit includes storage and comparison means to store at least one limit value based on the heart rate or its time variation and for comparison with this limit value for output of a control signal to the switching means when the limit value is exceeded.
Moreover, the parameter monitoring unit expediently includes detection, storage, and comparison means for the monitoring of at least the battery voltage and/or the impedance of the stimulation or shock electrode arrangement and/or the stimulation pulse amplitude for the output of a control signal to the switching means when the battery voltage or pulse amplitude falls below a limit value or when an electrode impedance limit value is exceeded.
The mobile phone terminalxe2x80x94which can moreover be a completely standard mobile phone with the provision of the above-discussed special means for emergency activationxe2x80x94has an interface device for connection with the body signal processing unit and/or the therapy device which includes encryption means for conversion of body signal or therapy device data into the data format of the mobile phone network.